<p><b>Abstract</b>—We consider the problem of providing per-customer service guarantees in a high-speed packet switch typically situated at the edge between a set of customers and a service provider network. As basic requirements, the switch should be scalable to high speeds per port, a large number of ports, and a large number of customers (macroflows) with independent guarantees. Existing scalable solutions are based on virtual output queuing, which is computationally complex when required to provide service guarantees for a large number of macroflows. We present a novel architecture for packet switching that provides support for such service guarantees. A cost-effective fabric with small external speedup is combined with a feedback mechanism that enables the fabric to be virtually lossless, thus avoiding packet drops indiscriminate of macroflows' behavior. Through analysis and simulation, we show that this architecture provides accurate support for service guarantees, has low computational complexity, and is scalable to very high port speeds.</p>